1. Field of the Invention
Embodiments of the present invention generally relate to high speed network interfaces, and more particularly to gigabit Ethernet over fiber optics.
2. Description of the Related Art
One of the more recent developments in high speed networking has been gigabit Ethernet (GbE) over optical fibers as defined in the IEEE 802.3z standard, one example of which is 1000Base-FX. Able to provide 1 gigabit per second (Gbps) bandwidth in addition to the simplicity and available transmission distance of an optic Ethernet connection, GbE over fiber offers a smooth, seamless upgrade path for current 10Base-F or 100Base-FX Ethernet installations running at 10 megabits per second (Mbps) and 100 Mbps, respectively.
Despite the increased bandwidth of gigabit Ethernet, network switching integrated circuits (ICs) have grown in processing power faster than physical link elements (e.g. network cables and connectors), and thus, the switching capacity of linecards has outpaced faceplate densities. Because of this, the data switch on the linecard will be undersubscribed, and the unused bandwidth of the network IC will be wasted whenever the faceplate jacks on such a limited density linecard run out.
For example, the SPA-8X1GE, a GbE shared port adapter for use with the Cisco CRS-1 session initiation protocol (SIP), can hold 8 SFP hot-swappable optical modular transceivers operating at 1 gigabit each for a total faceplate bandwidth of 8 Gbps. SFP stands for small form factor pluggable and is a standard for a new generation of optical transceivers for use with LC connectors (miniature fiber optic cable connectors that use a push-pull latching mechanism) that offer high speed and physical compactness. Returning to the SPA-8X1GE, the linecard itself has a bandwidth of 10 Gbps, and the next generation will have a bandwidth of 20 Gbps. If only 8 Gbps is used because of the physical limitations of the faceplate, then the rest of the available bandwidth is wasted.
The basic conventional industry solution is the brute force approach of increased bandwidth per port, and 10 gigabit Ethernet (10 GbE) was offered as an answer. Even though 10 GbE does increase the faceplate density, it does not solve the issue of aggregating enough lower speed legacy links to fill the higher bandwidth ports. In addition, there are physical limitations that prevent 10 GbE transceivers from reaching the low price point that transceivers operating at 4 Gbps or lower enjoy.
Another approach to increasing the bandwidth without the additional cost of 10 GbE is to connect multiple 1 GbE links. However, these links are channelized at higher network layers with more complexity than the physical layer, and the router software may be very inefficient at managing all those links to replicate a single high-speed link. For example, one would think that five 1 GbE links should provide 400% more bandwidth when compared to a single link, as long as the system could support the cabling and information concatenation. However, in practice, due to routing overhead of higher layers, these five links may in reality only provide 50% more bandwidth.
Accordingly, what is needed is an optic gigabit Ethernet system that achieves greater connection density, preferably while still working efficiently within the boundaries of existing GbE standards, transceivers and cabling, while maintaining backwards compatibility.